Importance of Microstructure and Powder Size on The Magnetic Features of Nd15Fe77B8 Spherical Shaped Powder
Sultan ÖZTÜRK Kürşat İcin Bülent ÖZTÜRK Uğur Topal
AbstractThe purpose of this current study is to produce spherical shape powder instead of ribbons by melt spinning method, and to determine the influence of the microstructure of produced Nd15Fe77B8 powders on the magnetic properties. Furthermore, high energy surfactant ball milling process [1] has been applied to investigate the effect of the particle size on the thermal and magnetic features. In the first step, Nd15Fe77B8 spherical powders were produced single roller melt spinning [2-4] technique using textured surface copper wheel. The surface temperature of textured wheel is reduced from room temperature to -5 °C to increase the solidification rate by externally contacting a coolant block which is cooled by internally circulating freon gas. The produced powders are dendritically solidified because of low cooling rate of spherical shape. The produced powders were then subjected to surfactant active ball milling under protective atmosphere to enhance their magnetic properties. Coercivity values of ball milled powders significantly increased with increasing milling time and decreasing powder size. The coercivity value of produced powders with room temperature and -5 °C were measured as 875 Oe and 2200 Oe respectively. These values are increased to 1715 Oe and 3560 Oe after 390 min milling time.